title: Overexpression of 5-HT2B receptor results in retinal dysplasia and defective ocular morphogenesis in Xenopus embryos.
abstract: In vertebrates, eye development comprises inductive and morphogenetic events that are finely regulated by the coordinated action of many intrinsic and extrinsic factors. Recent evidence suggested that neurotransmitters could be enumerated by the extracellular signals contributing to the retinal and eye development. We showed that, among these neuromodulators, serotonin acting via the 5-HT2B receptor, is involved in the control of retinoblasts proliferation and survival in Xenopus embryogenesis. To further clarify the role of 5-HT2B receptor in ocular development, we performed a gene gain of function analysis in vitro and in vivo in Xenopus embryos. We confirmed that 5-HT2B overexpression is per se sufficient to promote cell proliferation in a neuroblastoma cell line. The in vivo experiments revealed that an over serotonin signaling, via 5-HT2B receptors, resulted in the formation of eyes with an irregular form, position and orientation. Interestingly, we showed 5-HT2B gene expression in periocular mesenchyme that represents a key signaling center required for a correct eye morphogenesis. Moreover, the 5-HT2B receptor overexpressing retina, displays a disorganization of the typical laminar structure with the presence of retinal cells scattered in ectopic positions or forming rosette like structures. On the whole our data support the idea that serotonin signalling has to be finely regulated during eye development to allow a correct retinogenesis and may participate in the correct orchestration and synergism of all the factors and events that regulate eye morphogenesis in ocular and periocular tissues.
authors.affiliation: Unità di Biologia Cellulare e dello Sviluppo, Dipartimento di Biologia, Università di Pisa Via Carducci 13, La Fontina - Ghezzano, 56010 Pisa, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Reisoli
authors.forename: Stefania
authors.initials: S
authors.lastname: De Lucchini
authors.forename: Tonino
authors.initials: T
authors.lastname: Anelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Biagioni
authors.forename: Irma
authors.initials: I
authors.lastname: Nardi
authors.forename: Michela
authors.initials: M
authors.lastname: Ori
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005123:Eye / Q000196:embryology / Q000378:metabolism* / Q000473:pathology; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044403:Receptor, Serotonin, 5-HT2B / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000002:abnormalities / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation; D014982:Xenopus laevis
chemical_list: D012333:RNA, Messenger; D044403:Receptor, Serotonin, 5-HT2B; D012701:Serotonin